The majority of breast cancer deaths are directly due to tumor dissemination through invasion and metastasis. Cell motility is a fundamental and indispensable aspect of both tumor cell invasion and metastasis. As such, cell motility is an excellent target for therapeutic intervention with the potential to decrease breast cancer patient morbidity and mortality. To better understand motility, we studyintegrins, which are receptors for the extracellular matrix that transduce signals that are critical for cell motility. Recently, integrins have been shown to regulate Protein Kinase A (PKA). Importantly, this regulation of PKA is critical for cell motility due to the involvement of PKA in the control of Rac and Rho GTPases. However, the mechanisms governing integrin regulation of PKA and how PKA regulates Rac and Rho are unclear. The long-term goal of this project is to understand how integrins and their control of PKA activity promote carcinoma cell invasion so that PKA activity may be properly targeted for therapeutic intervention. The objective of this proposal is to understand how pi integrin regulation of PKA activitycontrols Rac and Rho small GTPases in the chemotactic migration of carcinoma cells. Our first aim is to determine how pi integrins regulate PKA. Our next two aims are designed to elucidate the mechanisms by whichPKA activity regulates the activities of RhoA and Racl. In our fourth aim, we will identify which PKA subunits are associated with breast cancer cell motility and dissemination using surgical samples, in vitro motility and invasion assays and animal models. With the results from this proposal, we expect to delineate the signaling molecules upstream and downstream of PKA that are required for cell migration so that we can intelligently target PKA for therapeutic intervention of late stage cancer.